SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f52f70126423c645bc78712d5bad9bdd76ac177d0fd261787849be6dee633fd' 
  AND token = 'RU+T9CpDXliiIZbNY0mZ3qdELGKxEl66L8/YUv99vzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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