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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9e0cb9a7030ca0947d0a49874b981b4ad8e5bad4edb2b0e5157f0318e183a7c' 
  AND token = 'Z7nK6ZxsL4UNKQ+tMTven/tqcFZ+yYv4Q1n8BVPjpf4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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