SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '32a15c4e608dd524361a13a8834958e1479462de91c07c6d4ac7fcb0e861a296' 
  AND token = 'yUzjCjCHaef1bHnygFos8wym3Vt+jpDSohVjk8sJk80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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