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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd88c2488be32d853723fed296ff27bed20496a2c9ac8dfd60a621e8b2bbd2a5e' 
  AND token = 'eCHJaxC6f7hNIeXYYB+F2TUBqwQDkXHxteKDg+GMvk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}