SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd849f68b63bb21984f530f56bc2d6920ea031891c1544159dd5e0cebcea95940' 
  AND token = '7/cPWgr3dtZR1L9Bq+/WlzGJwXOLbvjED8FkZkSMb4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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