SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0867342358c69cefc9853e2f2d1a7a700b6f9d82840a99e83984b1f9efbcaf32' 
  AND token = 'r+V5zFzMpgImUef0eylGsFkfuCLIZ4ygoTcnivVWZqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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