SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08d555e02ceb445851f809bc01b7126f3f0779ffd34759dcc0dec42558f63850' 
  AND token = 'u0BXQYCG/6d/xyKlUMhLGytrN+BlPZ6nxXz7eNe4JG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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