SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'eb44988f99b8bd60ecf4f04bd6c2296abf9c56d1f5053f90105abcb76dc2b971' 
  AND token = 'xn9lu4S34udRYH24MAD2jVf9B0vw0tQC+fTdb9Xwp/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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