SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dafa6c2ee8d54222a7db8202d2bdbd3830244b896680fd092fec7c8691ec447a' 
  AND token = 'TSchOZrbmsr+RRAaexYyJRDwG7ysmNrwNKGvYkZ0d8k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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