SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50637f9ee5978b5928ffe4d8218cb61d74b4bad3f44b2fa754576c02d2b82503' 
  AND token = 'fEdVT8NEW+JpbNxwKh4HGWH6Tk2SnyoEZZVYAWuvmXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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