SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8d57a006b826853260fa04888252e0c01bba15c75655f03882fc7842fa9c4d6' 
  AND token = 'gKMt76rJir6iGnpvuRsPaZxy7kqRhBDd1pPA9Og16xY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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