SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '237fc11cc4a38de4b901212e695517d7e42c2d491de23756960ffa390200c84c' 
  AND token = '6tIm/LjC0Vxh4JMww9JYm/hbADzndB6YAqOc2TVh6HU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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