SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1d753cb4e180945c1696771905f2e1b99526b423b5fbabc725fbfcadb6e5dcf7' 
  AND token = 'ov/d90CPTLiLnno9PEQMqneUBiNvKyLhh60qEdc5+Wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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