SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '45f6210fa4b6bec4e0c12f5458042da8e8d0b2aba9255916ebdfd9f65083e3e4' 
  AND token = '7HuTJ/mgtwbpRBHRpvjJtyAsf//o+RMaupxQeVJW6KY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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