SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b57ce3cf4abe1bfe395230fa12a7f721ccc89a212641ce410a5e1d70c13fb16' 
  AND token = 'MYiL0SOvJWMx0wMVuUeX42Rw0wyWFHpj4/uokEulRCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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