SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '54573668d658cb8350bab0e86c6963c0034934b1571a5b96f4b1e2a5d0391fd1' 
  AND token = 'k3o32R68NpzVbnypUWcrBu4PJmwgzhBT34Gdk10rjyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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