SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a948e3e01504fd98a14bb281aa35feadba0fcbda9bfaf536b3084362e8e40645' 
  AND token = 'cWVht8kn5VqR1aWWJ1iuZYKsxLBHliesryLpZj1pj1E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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