SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '918f3e71a997822a3e973bb8e51ea6ae8121435e747888fdc414a1954470ff9f' 
  AND token = 'attywUqwQO5gq5WwMjf4Mj7af7uGsp4FuwbnTyj88rg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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