SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '511d7d3136ee5c0555639eaaa2537c6c00b05b570045253051e0cfa36846ca42' 
  AND token = 'Anr+JigQVkPGSC81m1JELKhlM9nEQEN3ka9nBX8Ws8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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