SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fe9e1950c4f96a742a2d69f4c6bb50e18b7f43bb75ee18ee9b7c0c3d2706bf2' 
  AND token = 'g+B9c/OQE+osvPGXqJWw1Q4TL3JAxMyM9mSTKWdwnvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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