SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '951312a41ef9bb281b5e2fa3dbcd43c8f937777012835c2db56384b828f9f9ca' 
  AND token = 'hFMfxylUnj8JAJhgckJd6ANLpELbzFhkSDy8QBKZV20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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