SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a12b90d3f5dea5d67e17f48e2dfe5ed68fb609b1588f1aa85edc2ff1149383e1' 
  AND token = 'qhHoIV8EiFb8xulkQg6sfGJHAH7Fay0YcqxSiiUzNog=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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