SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83964f9f40aaeb2ee03b1701753efc82b37b46ffaeedffcd450c9809a89378c5' 
  AND token = 'RlfYDAht4zx6e4E54yKinxeOxQbsdj/Mm0xIyV2HEo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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