SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52c28a051a9e9d0ea0d690e129e81c8ff3f31883ddc3f26e004b7b87a4a7c4c6' 
  AND token = 'pZDI1JLISgLCne61gBpujwIwOUdzQuiHpFZjOx+VX70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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