SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7c18d3d6a8577490b8016296bed94a5772465e538074a8be28092a7e595043c' 
  AND token = 'lpFUcBDGRUhw89WvXrSfH+lA8khWKTOKCFZJqSAt3xY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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