SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b98893f42e7a281e16fcd578146cfdadf5d26d5d31c626166c2f02ca61f919b9' 
  AND token = '/33MtBjmLepxL3diSmimwvRnlJrAa/mUeWimEA4Mgig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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