SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c856f817b916491a2835f4ccf7edd975532939fbb26c27455e699f31db42b12' 
  AND token = 'tcz3N+4lyLUg3eCwZtwgzfPagF+uLaMHdV8rIXTZDjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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