SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50af3d57ea9dd1b32c7dc53e55806762db981f64ab0cc404ba10a62230629842' 
  AND token = 'LhpFyOXWuGiHITjpQcugqWYCstJH1pYMY1KWQhu9Xcg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}