SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c18d5c938adc0372d65bf68b9aaffc13b5f0980ec3250e0dce245ae67d571f1a' 
  AND token = 'XpxqTnSo8xRfeHtOSQzzB2oghEOKeEoRMNnkbKiFrm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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