SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e6dda0129101bc23b2f53c938b932cd2076704c1c80e8ebd547898e7848b0e1' 
  AND token = 'RKzrwz2MQjoFZzYVjeMNV6QPITwzQDPNhbsw4c6lwzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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