SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2c731ea69805539ab900ac369b4a5b2f26de12be53fbc636ac1f95508401018' 
  AND token = 'dKbuaQGlJcjVi9TcuKkc5tcRMeuCbFMw9rTUG2P4IvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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