SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b16378c6e97553b05db7af22ef433612b14edb1087eed732221227a4a2fc37f' 
  AND token = '2umGZL9Q1AfnssttyIkCDHAQm7Nnr2zVK0Sakq5JaGE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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