SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '356b2f1a05c879240c2864b1c7d979e38a1581530eec7c31d7680bfc5d6524b4' 
  AND token = 'weoI2Djn8AvOqZ6Uo9Qkml1+bBNuLUkGx+vzDlzLD7k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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