SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ac786dd8939d3d00c02aca67717878efd15ad886b73f9e74504cb909852d45b' 
  AND token = 'ji93n4RPmidMJvyhEAr/dJQjJVTPhRaVDHeBAylfF18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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