SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2ae33cf3e45f554b81ad857c222bfa42eb8eb371d339024ccd10b7600d83a2f' 
  AND token = 'FL+MKvidGfBe4WqKDPfPrY83aLYMkJOvqlItA5j4j14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}