SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6570cd97073c8d45575be9b3450097fe99b3bbf5a4b29e42ee8713f119eafab1' 
  AND token = '75koQSrrvtsXe/OducVlFhhjxWWZnMgGiq8zscIlamY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}