SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b4ee7ba60524461a8b165693e398d8bcc6c962f94fcd5d17e9823c18b95214c' 
  AND token = 'p26+/xaaMbwWWMGPaAaTGb+R6s9zQ6T0rcKKlBAv2yU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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