SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6fed7279c28f7cbbf2e87bf698b5fbbbb464e42d80abe4b5f66905784ab64aa' 
  AND token = 'CdrTlxsiHRULqkE/TnsHwtzoLldgIjnCjuSC4hOYCzw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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