SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c4bd39e65a0296513abe1cf9d8174e8ce21776399cd108ba09e9fc5e3c9570f' 
  AND token = 'Cq1T2Gtwb5y+Yf9EwTDBhfYJJ/UDbU+nHoqF/On1vlI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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