SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35b10cfe6e188a26c580f62a2fd413bacc357f8f3670048cde9eed0893a7f128' 
  AND token = 'IM2Ttm7RYUaH+QZS/5kc8W3bOE/AxcQRBefH0wEqFgw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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