SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '283c38b8785dd929bf7077e91722502ef9a7a873ef5320e7906a818aef6dffc8' 
  AND token = 'SDojH2Rpc6Vzt6oAR994YGFUkWdl61StPSFLExBxaqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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