SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c8496981afb3fe311b53c106fd4653adcaf347de36e5c91f6a35b212af0b6916' 
  AND token = 'rOFQegCHExQfrWMq5jQYoRhOeBu+2RdJySndfob/zoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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