SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '496cf98238f2936c6cb72bd91c067f181404662d50c09f5479a3587f36559038' 
  AND token = 'fxty25qtNt+ix+rps50QDzRGylFc6jGrYIl4E0nMMjk=' 
  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"
    }
  }
}