SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c1b3a1bd6a847ff4bdfb4bca41a0f36266d15920a40ded112bd7a83e7251be6' 
  AND token = '2olBCl/hw9eUS1ibo4ahnjM/yDJAVQ/45ajD+kM/x8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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