SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ee735573e0ca66b0c70fd2b8ba89fad5e6a3b7d4ba51137ccba0f9db6e8f835' 
  AND token = 'qNSL4NSEG9Xs5iFSmdrpj2B6CEnOIoEYbwizdSIj9Fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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