SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c8f06ec3ef44d6e7cd432eb68f829e2a944e5260a252bd884a816c7f788a54d' 
  AND token = 'uKRKBrNWbh/9vsVwbYiphByjaBzsQehN02+o/uwmRZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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