SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9ea64684da4528e6426425ae0507f3284f40bfd405790469e0a917c395f3b24' 
  AND token = 'QTsC6kgJT6tHADqJpGNd9nr0UwnZ2PiiDdailhvwyaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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