SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47841c2db5ea1480139803e68e53d7c276f9d22586e57754f373f6fe7484607a' 
  AND token = 'DiHIoQZsoodWTaZeiBz2HjoMJmHObMtGtfRThfWsQ98=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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