SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7dbe2c8a7304c507f442d770d2605c5136a4538021f41e4910890c78a8d6bb4c' 
  AND token = 'kNQousBxvWf2ofBhRVbOac4DEA23kq7hZrHaU4bH5ZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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