SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f5472d18e50313da63aa378a9a24eac52b0fb88fbaf711b85b75489dc54ffe58' 
  AND token = 'lJHZUMZT3DRkBUX3FWMSm/El/sxK2XXaO8zdDrCIgts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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