SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6691ad8241406f8c81b48b01995febbe729c4e5709585fdbad55c820e687c9b3' 
  AND token = 'yYOmqGqSJXQPSt+hYqtCVXbrATiMwHxhi9/rCDmz27o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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