SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90074bff6c55a47d499099643ab29a04508f798c503bbbd6b1903daae23b87ac' 
  AND token = 'XZFGMmyrfhYB6G9yuVJcVlFcjgyeAjE6XePhpf6XTj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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