SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12becfda4a57e38aa455e32d6df550c52cd0741e5aa7d357da4ad11623fd1bb3' 
  AND token = '4Nc6hWpsoqtFIyWcsRXaEAIsv1lwAW7uN6k5jWl3Ev8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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