SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5067887e435bd5208f3a9b0f42e9e673f6c038a4b052b8665993d79640fedcf' 
  AND token = '0vcqopJDa3emM2AfsUI5ffcCQIHAuNjTuqoNVin+2NQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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