SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42454898011c7ee9bd9922fb42cc42946dad2a5671231a0b7e6e7178c531e644' 
  AND token = '4LLATmft2VibdMSEb6trD3X2JrIzzv3QTrZPLk+DyXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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