SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bdce7393872edafd96facf135bc05aada7f546a99852f11698d317b0243363cf' 
  AND token = 'U6Q5aVEp91c7MMXBSUJnighyn5ZutPpD3jhhbuM4uDA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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