SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c53229d81a1cd010c124c8434b562d404afa387939e5a4020828429cf294b5a' 
  AND token = 'tUgIozepxHbJ6yd2es3uRkDiogfH+Y3VaCd13zkrmQU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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