SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9b358080b8647cec518b8882e7d9233018d277183031203db9b0055e79a11fd2' 
  AND token = 'YKS2XsNRnhOC3wgh0qJYnv6pVhG6XzviQqtwj7G1Yd0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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