SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '298e302db4bc3294351ba75ad9cb29526273f559b4098c192a0f356081dbd843' 
  AND token = 'aGDOLvfsxK6YE/i3XrDz0i1gMolGZg7Y536yiXuiG3I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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