SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a694bad56b8d8bf1cfcd6b8a3aa3a80b58325142d481a480d5039baf6b3e666e' 
  AND token = 'yDPUqKmZawpKfiy5hxLkqOgRcu4+YIxWlhAFexvmkQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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