SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b74564b32a807c5ee07e8bcd4562ba7b87054bc0b4b3179028ad1b4b9f9b763d' 
  AND token = 'KKwUCyYE/8GTpzEnXWFohLg2SD2DAELKVh32hU/ZunQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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