SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fa0b0bfa260c95159dd1d3ca7c50ea29efe862603ae67bfa8c7bcbf2f5928982' 
  AND token = '5zpJ80H2s0j0CmkUik7t+3lth2w3TfG76bfkanvOUgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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