SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64ed78c9341e316558d2f225bdac06979690fd304cd57e67f88d0dbb5536891c' 
  AND token = 'DwXPuKmG2Xd/DdM4zdJ1WsuYKzbNo+VLvkv9CAMFHxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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