SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bb7d79b6e34cf83fb003b42c749d416ac3b90c4d402e7a335a44394d12fd7587' 
  AND token = 'wDegMdD6vI2xEfIRmuZnaDcorMozfCuLk3MV1zBIBxQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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