SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87feabba0d512104e1922a3570676d573660c8a45a85d4c89813d92aafe6674b' 
  AND token = 'IPn2HDERKwgWBMDbbApqzwrVVbvn9UuEwEwHOAJcY9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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