SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a9854c0390f014067db55e5480999d00243db9ed5d02839b110ecc523e21c6c' 
  AND token = 'FpN+AmC+JrEaa0WgoRuQu+3MK7Z4ejTzqY1I/vqT51k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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