SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b90ea45e8d6fb5888111241ef09b03e2571c6555718aa7be3e586246b568146c' 
  AND token = 'kbdJJBlyhzB9V+dw+lGjZCYcXGpWHLn706dGaI4tm7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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