SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7775fd8d64c931cc59f63243c5030abba1ea41f3ab7610013e7842e278b6260c' 
  AND token = '6hLoSzm9KEolRz9KMybnJLvtXeej7glSHItW6rZDqgw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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