SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a37d0c55518b411855424fcb055bf986171f3ccaedd86a3d5a48da81394022cc' 
  AND token = 'YuvgGyc2EpunoO750ThIfEFXwIv3NVIlJxFDfEYRPVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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