SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5108c9c5889d489d12154676a39504fdf2c27775a47f3200c61084bbe2e7189f' 
  AND token = 'Ecn0gMilKohwvBwjbMa4yfadCWTnlsRdBvkbGBxFAd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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