SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23e7639054dd7c394ee9d0d086eead5826eda9676d4686bbb891112b0a62ab16' 
  AND token = '+Arbm9/dyHTLrH40KRwjajNblrADKERBQmibAPm2HEU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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