SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '93b1a1cfed03ed0edeeb4b41f78ff66951a2dfd1532186970c1c2880f42cbb66' 
  AND token = '3U/tAKwbvPaEQUF7E6DtMsQcD6GN/uMRHx4VmITV3QE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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