SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c6d07295a19211571919e5d14cd62daa69cf5cfa639373a5f588d52653fd032' 
  AND token = 'I3hXpHi55o7g+o6c+sWQKLKBzrwK2YNx3DGxj4VDrJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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