SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b91215b55ab731d0d359ed3f54da2fa41e7a65e9a41bb20bd0350da8338beb6f' 
  AND token = 'Wj8B2co/bTVvLGDTDOxXUGq1YvnGHOdN7ITajfYv1P4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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