SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f14f23ebf9abb03fd1f6d3ff02f109e313b2a0932435bda7dc29abc0c5bf9f0' 
  AND token = 'fqR23ojxuAqY/MF2WmIn1/ePvl1WGuXGjEr196cUaNM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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