SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd2d3850c733aa2ebc5bc75188868e326e1da9fdf8daa02d5eb7a590a8d8d872' 
  AND token = 'YtN2wgK4LSrjC6tdNJqn1kzh8Eqt/MlZPXZmFBxDzT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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