SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8bccd8a542a77a6f8b18ddd903ad3fab646636e516360e7700096d396f701b5' 
  AND token = 'PXcDiPK3zPYutjz2uECzK2Len04teEYphC12Qkt5WNE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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