SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c849bc35287c2fd7f375ae3e9633b79c3a266f02acf4d46d85419078f3da9df' 
  AND token = 'jQ0IyhkzqWVInALfSw6/NsSknaAA5GcqAiJ71R1KES8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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