SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39213b5cfc599b89478852c5c8f48b88c453472ff6f861151a6c0d3970c947d2' 
  AND token = 'AJ86OCgZJXQqMOjDEFaPiA5v3TB13/PRWGSLQgKng4c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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