SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd15fbda617f12647e895a781a5494aca92fbb063f0ca02076563778ded5119a2' 
  AND token = 'j1+uL40anIIJGoFzf83VKmgiw0ct5zYTgDAkMaLyYT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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