SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b4a0b54a88a8a79411232e635a8b75e7dca91a82073374ededdd0b195834c41' 
  AND token = '0NbJISxjGOW2Mtu8Qjv1ZPAKsp1k3Qp7QeSQ7G+dE7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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