SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd42a66a99fffe7c9cd7071ecacdb660ee082adaaed2b5c79be56359a5044a293' 
  AND token = 'GdgxDlVcthsJ8tED8ymkLRQTveaHaDAzczAmn5zqRBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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