SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3d7cd8317be33674029a43694623a04bc189d0f7225cf7c829dd3e259bbcb15' 
  AND token = 'aV6BtEpv/urujmUh/6Gch6nj254pngh2+8YhzFBiArE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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