SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08d4480ef83c2f2ec666ce34557c3444cc6e4be5d57bf18ea4888708a9a60299' 
  AND token = 'MgNF4CAYDqkvRRQ5iuElJxvo+vBxGqtTTARqtMWTHdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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