SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd650b1fbb3d237e5b9520ede735ef5575612f78c6fa192a7f4e93fa704ec838b' 
  AND token = 'TuzTugCwesYFj7SuMQVHPfHuz+q2dP/GpUUw+7vKlqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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