SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df429397a1de60516d54b54b632bf79c0b62753a823c6d4a7261b5630749d4a4' 
  AND token = 'yhg/HBnQFD5Yf4ezCyj48ilK7kI8XEE2EsFfSYguz/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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