SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8558166f0784fb4c88e50ce4cbe1cd507305a4208f931cea4f2f6fe1ccd7cad5' 
  AND token = 'DdNI3WiPPI1ccHCb1GHtiQ/hK+PIdaDKmsGIgULNMIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}