SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '591a41db451058d54b123bcefbd41e246aa75ef1b587031da8dfe606a1292074' 
  AND token = 'HrjhbTb/4LJRcWWJ7wLGCdqBW2okbLhKkbxUwt0jizw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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