SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '353e8dac34655c5768827ed534c1d6aefa8eac14d7a5e5aa380c7998d0792628' 
  AND token = 'tETARNQAmQTzoMcSX5LBgOW2npsbcAOmY46tubmwvCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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