SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffc643ced42753998ea455c332624f91fdef2b367fd2e01f61408d540de62ca6' 
  AND token = 'E5Xb3kakwFqdlHL7dXz3voQuV4RQ7WfXO+29GVoGVI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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