SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '03d33b4c97f24ba79240778f90248dd09d4721095ecc761c922854163de1cb54' 
  AND token = 'RbFTprzdKGJIxHKtzSPqQ876etFZufPe39eAyw/hQzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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