SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '610ae5f97db763f58c809ac2d66e2afb74be7784e472a4d680ddf9713a66b278' 
  AND token = 'aY1pIjm9wusHNU1rod4m10c2I3NhK7KkQdMszTGDVEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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