SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cbb456aa77c18edd3be5597a712cea4a553d3f83e29b43a913da12c90dc93aa' 
  AND token = 'KPqidI3W9wrQtPN811icofBMlGMkde92+HRYdymaVTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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