SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e61d9fdf8491ac31a3e1862f01f15c40dd5bd70ba3b90bc8f8461df0d5d68f97' 
  AND token = 'OQNXISDYFgvvlxV88PUgU3bvbPtB1+3mjRwqq7wiQVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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