SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f68802708d299a04ac0ff3d1ee536a4e578439d9d87878687958234c05d02cc' 
  AND token = 'yiaE2icMsJ0JfHp252NWvsthostthkbS2X1VMQf6uXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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