SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'eaf6c993383bec06a93099b820500d5082432110c70e652b812a75cbf2df1cc1' 
  AND token = 'YVmnJ9f+rFEBxiwRfOtBSbMC7nwL/O0+B15JN28j//Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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