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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2783f5694e46e1c17c67f9d3424c49f24ae5600fa20664faf7e4925618ac260' 
  AND token = '9L4tjah7RcA1hj/1+Un0dSSy+zESFxtiDr6V5RfAA54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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