SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '27adfc3080b7bd80c05c368549dbd8424702de8fd725f9a6c3d9488f6c4154a9' 
  AND token = 'OAE1yFIXqI+TS75EGtClomuKZMtmjQS7hVfk0COb+wo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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