SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55fa5f333f1886d193a4f41a13100968e4000f1f6c234aef09f2610e69b00adf' 
  AND token = 'STstUBfDgbDXWGKVG99L+VMnMyjmKgMnxieLmY8Hgg8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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