SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eef6be729a317473ae41e785c56a479a5abedabde42042d38f00806c8841c0ed' 
  AND token = 'PF9UebXQIuLU9SVuMSwUK/2uPExckQ1WymtDEotfZnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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