SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a2514b24b2287346e76d4dff03ec6bd387cd182d45586eeed075aef1cbfb9d54' 
  AND token = 'zPeDyIiV1OUf9wXPMGbwBmv0dUniujHghE7QqtQcq5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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