SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0819d01851477a4b93c3de97af692964f6dd9445542a3ff0bb9550df44529d26' 
  AND token = 'H+g2mS527V2ucE+dYMKEOmstDDDD5uFuONkW6aEPqFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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