SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40205bbe2a6b467e83d998c2e437a809a028095678f32f918ebb55d38b21a763' 
  AND token = 'fx+YAdDVWjkhN9BZoWpyVbABubvTrUIzTnRzCWwZ/Vg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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