SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b231622244ef37c2988fdfb6b8f22bba4e3a336c7ac5c2c83c1cfb23dd155924' 
  AND token = 'kI9wezzyEjQaPR6+Y/Xw8vM0JvOHtgO3h+4f6BNFKF4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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