SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02104690d62b99d374f40d791c880445c794256286a8ae7aff55bbf8062ac94f' 
  AND token = 'YJjR3zp4GUILSuxvR7WncGjvKy+BbDxJs4kaMZ+DB2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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