SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f755cb8286d2ff05719df66e3361bade4be7b63f66d2585b7ed61db1fb7bc7c2' 
  AND token = 'xsuSfa/hYgNoKuerAqaywxVmHfMI2+Bw6tGu2DhQmTg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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