SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c12f25837fa7989f9e52e9c8c273dab90b61ba0caa2df4ea5f06e3f9bbc35afa' 
  AND token = 'QwsV9Z7VQMFt4CB6SccvlYgrPBsgdPLjj+M/HXQVDg0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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