SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8200f7608afc696f6d14571ea17fb2803d1e4adc585403a92d9fd1cbe1205f35' 
  AND token = 'Wc0gZLWx7/Wm9z+ETURnMIWJoiTLWk/x3ABng8TO2pE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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